Missiles fired at aircraft are usually guided either by a light seeker or by radar. Of the various types of seekers, infrared light seekers pose some of the greatest problems to aircraft defense. Unlike radar seekers, infrared seekers are passive and do not emit a detectable signal prior to the firing of the missile. Pilots therefore have little warning of their presence prior to the firing of the missile. Infrared-guided missile systems are relatively inexpensive, and human-portable units are widely available.
There has been a continuing effort to develop sensor systems that are carried on aircraft and are used to detect missile threats, particularly infrared-guided missiles. The sensor system must be effective to detect the infrared signature of a relatively small-sized missile at as great a distance as possible, in order to give the pilot the greatest time to take evasive action or to trigger countermeasures. In one approach, a wide-angle, two-color staring sensor system has been suggested to be particularly effective in detecting threats. This approach uses a two-color “sandwich” detector in the sensor. The technology of such a two-color detector is complex, still under development, and expected to be relatively expensive when finally perfected. Additionally, it is expected to have limited resolution, sensitivity, and clutter-rejection capability, particularly when mounted on a fast-moving aircraft platform where there is a tendency for digital images to be smeared in some viewing orientations.
There is an ongoing need for an improved approach to a sensor system for use in an aircraft, particularly for detection of missile threats. The present invention fulfills this need, and further provides related advantages.